| 摘要 |
PURPOSE:To enable the accurate measurement of the position of a magnetic head by laser, by a method wherein a rotary oscillating arm comprising a magnetic head is provided with a reflecting mirror, said reflecting mirror being positioned in accordance with the angle between the straight line connecting the reflecting mirror to the rotation center of the arm and the normal of the reflecting mirror, and the position of the head is detected by utilizing the reflecting mirror. CONSTITUTION:A rotary arm 4 is provided with a plane mirror M11 at a point P (corresponding to the outermost periphery of a disk). Providing that the angle between incident luminous flux TP and the arm OP is beta (constant), the mirror M11 is positioned so as to be vertical to the incident luminous flux TP. When the arm 4 is rotated, providing that the position of the point P corresponding to the innermost track of the disk is P', and the rotating angle of the arm 4 at that time is alpha, the luminous flux which incides vertically to the reflecting mirror at the point P' is T'P, and the straight line TP and T'P' intersect in the point S. The angle beta is set at the value <PP'O(=pi/2-alpha/2) so that the incident luminous fluxes at the points P and P' intersect at the point S. |
